Despite a growing interest in Western classical improvisation among researchers, educators and musicians in recent decades, research insights on expert improvisers' learning pathways are scarce. In order to further understanding this phenomenon, we formulated the following research question: “What characterizes the learning pathways of Western classical music expert improvisers?” Addressing this question, we designed an exploratory case study, conducting open-ended semi-structured videoconference interviews with a purposeful sampling of N = 8 Western classical music expert improvisers. The participants are international classically trained musicians who are recognized as expert improvisers by their peers and who have improvised on professional albums and in established concert halls. In-depth analysis of our data revealed two distinct learning pathways among the participants: (1) native improvisers, who have improvised since the very beginning of their instrumental learning; and (2) immigrant improvisers, who started to improvise at a later age, during their graduate studies or at the beginning of their professional career. Native improvisers began to improvise spontaneously, without apparent extrinsic incentive, while immigrant improvisers started to improvise in order to attempt to fill a gap in their musical practice. Various factors motivated the immigrant improvisers interviewed to themselves dedicate to this practice, including seeing improvisation as a means to experience (i) a ‘getting back’ to oneself; (ii) an authentic human encounter; (iii) a sense of immediacy characterizing the creative process; and (iv) an equalitarian musical practice. Lastly, a ‘learn-unlearn’ process appears to underlie improvisational expertise development. Implications of these findings for expertise development and skill acquisition will be discussed.